1. Field of the Invention
The present invention relates to an injection molding composition using a propylene block copolymer used in an injection-molded article having high matte feel, a method of producing an injection-molded article thereof, and a matted injection-molded article.
2. Description of the Related Art
A principal method of producing principal interior automotive parts includes, for example, powder slush molding method, vacuum molding method and injection molding method. With the view of enhancing the quality, a powder flush molding method capable of producing parts having high matte feel has hitherto been used in the production of interior materials for high-grade automobile. However, with the view of reducing the cost, it has been increased to use injection-molded articles as parts such as glove rid, meter food and center console in the vicinity of the instrument panel.
However, an injection-molded article of the prior art has gloss better by far than that of a powder slush-molded article, thereby to cause a problem of a difference in gloss between it and the instrument panel made by the powder slush molding method. It has been known that a factor for deciding the gloss of the molded article is surface reflection caused by fine irregularity in the order of .mu.m on the surface of the molded article and the molded article is matted when this fine irregularity increases. Therefore, a technique capable of forming or providing fine irregularity on the surface of the molded article in the order of .mu.m is required. In the case of a polypropylene resin which occupies half or more of the amount of the resin used in automotive parts at present, use of which being increased, plate-shaped fine talc particles are used for matting. However, the molded article is not sufficiently roughened only by blending fine talc particles and, therefore, sufficient matte effect is not obtained at present.
Furthermore, a method of matting a molded article by transferring fine roughness on the surface of a mold used in the case of injection molding onto the surface of the molded article is used (Japanese Laid-Open Patent Publication No. 3-87213). However, the molded article is not sufficiently roughened and the same matting as that of the powder slush molding method has never been attained.